DPP3: Private Peer Introduction protocol

DPP3: Private Peer Introduction protocol

Add a privacy protecting variant of the peer introduction protocol to
allow the station device to hide its Connector from 3rd parties. The new
wpa_supplicant network profile parameter dpp_connector_privacy=1 can be
used to select this alternative mechanism to the peer introduction
protocol added in the initial release of DPP.

It should be noted that the new variant does not work with older DPP APs
(i.e., requires support for release 3). As such, this new variant is
disabled by default.

Signed-off-by: Jouni Malinen <quic_jouni@quicinc.com>